if anyone has knowledge on the 420a head please help. My compression is between 175-185 on all four. Although there is a small external oil leak, coming from the back of the head. the oil is seeping down the block but i only see oil on the crossmember, never on the ground.
should i replace the gasket or not worry????

dont worry, those numbers are close, it depends on altitude also

My headgasket has been leaking like that for 4 years and never gotten worse, actually its stopped leaking over the past year

420A is notorious for leaking/blowing HG at that rear corner near the driver. You'll be okay for a while, but it will get worse.

My suggestion is to check your coolant overflow tank for oil mixing in there too. If it's getting greasy, bad news. If it's bone dry, that's bad too. Call up Bob Kise 810-714-3300 and order the MLS. He gives a decent discount to 2GNTers. You may want to grab some ARP head bolts while you're at it. Those 2 just mentioned will set you back ~$180.

You can change it yourself. Get a buddy and plan on a full weekend project the first time. You will also need to flush and fill your coolant system too since you have to drain it all out.

Be cool. It happens to us all. :)

Yes first seems to blow and leak out, eventually it can blow and leak into the combustion chamber or cross into the coolant passages.

Get it changed, and make sure to have a machine shop check the head for flatness.



15.9 @ 86.7mph

Smooth idle? We don't need no stinking smooth idle.

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